Windows having a wooden sash which is slidably mounted between the jambs of a window case generally include "plows" or vertical grooves on the opposing sides of the stiles thereof which are configured to closely receive interfitting channels or other such ridges which protrude from the adjacent jamb liners. The interfitting relationship between the ridges on the jamb liners and the plows on the sides of the stiles facilitates proper tracking of the window sash between the jambs as the sash is raised and lowered, provides frictional engagement between the windows and the jamb liners, or engagement with frictional positioners located in the channels, to help retain the sash at selected raised positions, and provides some weathersealing between the jambs or jamb liners and the sides of the stiles.
Although the interfitting structural relationship between the plows on the sides of wood or other such window sash and the ridges or channels on the jamb liners provides certain advantages, this also tends to interfere substantially with the ability to pivot the sash out of the window case, such as for cleaning, and also interferes with the ability to remove the sash, such as to repair the sash. More specifically, it is typically necessary to push on the jamb liner laterally, or else deform the jamb liner, in order to disengage the plow and channel and pivot the sash out of the plane in which the sash is vertically slidable.
Accordingly, a window of the type having at least one sash slidably mounted between jambs of a window case, which is configured to eliminate the need for conventional plows and interfitting jamb channels or other ridges to achieve easy pivoting of the sash from the plane of the window and yet will adequately perform the functions of the typical plows and jamb ridges would be a significant improvement over the existing state of the art. Another benefit associated with elimination of the plow and interfitting jamb protrusions is that it would be easier and less expensive to make a wood sash without plows, because this would eliminate a routing operation on each of the stiles.
Known windows having a wooden sash slidably mounted between opposing jambs of a window case often do not include any weatherstripping. Instead, a sort of weatherseal is provided by the interfitting relationship between the plows and the jamb liner ridges, together with similar such structure along the edges of the sash stiles and the recessed channels in which they are sometimes slidably disposed. This weathersealing function of the plow and jamb ridges is not always satisfactory on account of small gaps which can develop between the plows and the ridges either during manufacture or during use. Such gaps can provide passageways for air to pass through. The sash of certain types of vinyl windows have been known to include a weatherstrip which engages the jamb to provide a weatherseal. However, it has not been practical or recognized as being desirable to provide a wooden sash with a weatherstrip, because of the difficulty which would be associated with anchoring a weatherstrip to the stiles of a wooden sash, and because of the convention of relying on the weathersealing action between the jamb ridges and plows of wooden sash.
As will be appreciated, it would be desirable to provide an improved weatherseal between the jambs and stiles of a wooden sash, and an alternative, improved weatherseal between the jambs and the wooden sash would be particularly desirable if the traditional sash plows and interfitting jamb ridges could be eliminated.
In windows having a sash which is slidably mounted for vertical movement between the jambs of a window case, it is generally desirable to employ a tension spring and friction device to support the sash at various raised positions. The purpose of the tension spring is to urge the sash upwardly with a force which approximately balances the weight of the sash. The friction device is generally in the form of an elongate friction shoe which rides in a vertical channel or the like. The friction shoe has surfaces which frictionally engage the walls of the vertical channel or guide. The magnitude of the frictional engagement forces between the frictional shoe and the vertical guide is generally intended to be about the minimum necessary to overcome any imbalance between the weight of the sash and the force of the tension spring, to retain the sash at any desired raised position while nonetheless allowing for easy sliding movement. An undesirable aspect of using a tension spring to balance the weight of the sash is that the spring is usually disposed such that it is visible along each side of the jamb. While some effort has been made previously to conceal or protectively cover the tension spring, the resulting concealment has been incomplete and/or not aesthetically satisfactory.
Accordingly, there remains a need for an aesthetically acceptable tension spring concealment device which completely conceals the tension spring irrespective of the position of a sash in the window.